Clothes washers generate a considerable quantity of gray water during a normal wash/rinse cycle. Typically, 25 to 45 gallons can be generated in a single load, which amounts to billions of gallons of gray water a week when extrapolated out to 100,000,000 households and 2 or 3 loads of laundry a week. Not only is the gray water generated and sent to the sewer or septic tank, but an equal quantity of fresh water must be supplied to the washing machine. This is a tremendous burden on water treatment facilities, public water suppliers, and the environment.
Another critical issue in clothes washers and dryers is energy costs. The vast majority of electricity costs for clothes washers is in heating water. It is likely that in the near future regulations will be placed on appliance manufacturers to minimize the energy usage of their products. Some steps have been taken, or are currently being taken, by some appliance manufacturers including a trend toward front loading, reduced water clothes washers. These systems still, however, can use up to 10-25 gallons of water per wash/rinse cycle.
Graywater reuse has been a technology area under rapid development during the past 25 years. The treatment and recycle of graywater (e.g., water from clothes washers carwashes, dishwashers, and showers) has been explored and put into limited practice for commercial and military applications. There is no consensus as to the optimum process for all applications, since the treatment and recycle scheme depends strongly on the size of the application, chemical and physical properties of the graywater, and logistic requirements of the operation.
Currently, most graywater recycle applications have been targeted for carwashes and commercial coin laundries, utilizing depth filtration and carbon adsorption. For example, systems have been demonstrated which use sand filters, centrifugal separators, precipitation of surfactants and other organics, and adsorption media. Other graywater reuse strategies such as chemical precipitation and distillation require several chemicals to be inventoried for treatment, and the processes in general are very sensitive to the chemical environment and temperature, sometimes requiring specific detergent formulas. Distillation, evaporation, or precipitation can produce fouling on the interior parts of equipment if not prefiltered or controlled properly, creating a maintenance nightmare. Distillation also consumes a considerable amount of power.
Adsorption and ion exchange could also be use to remove surfactants and organics, however, the inventors have found that the capacity of adsorption media for graywater constituents is limited, so these systems would be large. The water could also be recycled by chemically destroying the surfactants and organics in the graywater, but these processes can produce more toxic by-products, require the handling of hazardous co-reactants such as peroxides or ozone, and are generally energy intensive (e.g., ozone generation or electron beam power).
In light of the Environmental Protection Agency's (EPA) "zero discharge" mandates, domestic water conservation movements, municipal graywater recycle ordinances, and EPA thrusts toward low-water and reduced-detergent washers, graywater recycle strategies are beginning to emerge in limited applications across the country. The general trend of graywater recycling efforts is in the direction of membrane separation, with supporting prefiltration and post-polishing steps depending on the specific application. Prior attempts to integrate membrane filtration with gray water and other wash stream recycle have not succeeded in demonstrating an immediate reuse process. Laundry recycle processes were attempted in the 70's and 80's, however, many of these processes never completed a pilot scale demonstration owing to membrane fouling caused by improper/ill-defined prefiltration, the unavailability of larger lumen hollow fiber membranes, or the use of reverse osmosis (TO) which generally fouls easily and requires higher operating pressures and power requirements compared to ultrafiltration (UF) or microfiltration (MF).
Current gray water recycle/reuse strategies rely on storage of the cleaned water for eventual reuse, or, clean-up of the water to a quality which is unnecessary and essentially "overkill" for a clothes washing process. The above-referenced copending patent application Ser. No. 08/600,460 discloses a process using ultrafiltration or microfiltration whereby gray water can be immediately re-used for further clothes cleaning extraction without storage of the permeate.
The present invention makes use of this improved process in a unique system which washes clothes with no external water connections or drains, and dries the clothes all in the same portable self-contained unit. The operation of the unique system provides a self-cleaning feature to extend the life of the filtration element. No water heater is needed because the user controls whether the load will be warm/hot or cold by filling feed reservoir with warm/hot or cold water.
The present invention also targets smaller clothes washing loads than conventional clothes washers which will benefit persons in dormitories, small apartments, or other remote living quarters. Without washer recycling, the water volume needed would have been impractical in such situations to carry to and from the portable unit.
One object of this invention is therefore to provide a system which uses a minimal amount of water for washing clothes.
Another object of this invention is to provide a self-contained washer/dryer unit which does not require a drain line or water connection or vent.
Yet another object of this invention is to provide an apparatus to wash and dry clothes in a small apartment, dormitory, or other remote location which does not have the convenience of water connections and drain lines.
A still further object of this invention is to provide a process and system utilizing a membrane filtration element which will automatically backflush and clean the membrane at each use, thus eliminating the need to periodically disassemble the system and either replace or clean the filter.
Another object of this invention is to provide a washer and dryer system which uses less water for the wash and rinse cycles than washers not using a membrane recycle system.
Still another object of this invention is to provide a washer/dryer system which reduces energy costs by using hot water feed for the wash cycle and reusing the same hot or warm water for the subsequent rinse, thus eliminating the need to heat the rinse water.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings herein.